When a GPCR's binding site is occupied by its extracellularagent (e.g. a hormone) the binding site must change shape in a manner that can be sensed by a G protein. Further, the GPCR must be able to form a complex with a specific G protein, and it must be able to be desensitized by desensitization machinery that senses the GPCR's occupation by its agent.

G proteins have three subunits called alpha, beta and gamma. When the G protein activates the next step in the molecular sequence, it splits into two units, the alpha subunit and the beta/gamma subunit. GPCRs must have elements that recognize the alpha unit and the beta/gamma unit. The alpha unit will not interact with the GPCR in the absence of the beta/gamma unit. Whereas, the latter unit will interact with the GPCR in the absence of the alpha subunit.

Naturally occurring mutations in GPCRs have enabled researchers to study the relation between GPCR structure and function. This is so because when there is a mutation in a GPCR, it changes the structure of the GPCR in identifiable ways. The structural change often results in functional defects. By identifying the structural alteration and observing the functional result, then comparing this to a normal example of the same type of GPCR, researchers are able to determine which function the defective element in the GPCR should be performing.

mutations

DEFINITION:

2. In genetics, permanent transmissible changes in the genetic material, usually in a single gene.

See definitions for individual types of mutations under "mutation."

G-protein coupled receptors

DEFINITION:

G-proteins are proteins embedded in the surface membrane of cells. These proteins "receive chemical signals" from outside the cell (e.g., hormones) and "pass the signal" into the cell, so that the cell can "respond to the signal." For example, a hormone, drug, neurotransmitter, or other "signal" binds to a receptor molecule on the surface of the cell's exterior membrane. That receptor then activates the G-protein, which causes an effector inside the cell to produce a second "signal" chemical inside the cell, which causes the cell to react to the original external chemical signal.

receptor

DEFINITION:

1. A molecular structure within a cell or on the surface characterized by (1) selective binding of a specific substance and (2) a specific physiologic effect that accompanies the binding, e.g., membrane receptors for peptide hormones, neurotransmitters, antigens, complement fragments, and immunoglobulins and nuclear receptors for steroid hormones.

2. A sensory nerve terminal that responds to stimuli of various kinds; classified in various ways including by the type of stimulus and by the location in the body.

V2 receptor - The structure to which the antidiuretic hormone, arginine vasopressin binds.

mutations

DEFINITION:

1. Changes in form, quality, or some other characteristic.

2. In genetics, permanent transmissible changes in the genetic material, usually in a single gene.

See definitions for individual types of mutations under "mutation."

opsin

DEFINITION:

A protein of the retinal rods (scotopsin) and cones (photopsin) that combines with 11-cis-retinal to form visual pigments. The opsins are also named according to the color of pigment: iodopsin (violet), rhodopsin (purple), etc.

vasopressin

DEFINITION:

1. One of two octapeptide hormones formed by the neuronal cells of the hypothalamic nuclei and stored in the posterior lobe of the pituitary gland (neurohypophysis), the other being oxytocin. It stimulates the contraction of the muscular tissue of the capillaries and arterioles, raising the blood pressure. It promotes contraction of the intestinal musculature and increases peristalsis, and also exerts some contractile influence on the uterus. It also has a specific effect on the epithelial cells of the distal portion of the uriniferous tubule, augmenting resorption of water independently of solutes, resulting in concentration of urine and dilution of blood serum. Its rate of secretion is regulated chiefly by the osmolarity of the plasma.

2. [USP], A pharmaceutical preparation of the same principle, prepared synthetically or obtained from the posterior pituitary of healthy domestic animals used for food by man; used mainly as an antidiuretic in the treatment of acute or chronic diabetes insipidus, administered intramuscularly as a test of hypothalamo-neurohypophysial-renal function in distinguishing central from nephrogenic diabetes insipidus; it may also be used to stimulate smooth muscle tissue, especially to induce vasoconstriction in the presence of hemorrhage. Called also antidiuretic hormone (ADH).

receptor

DEFINITION:

1. A molecular structure within a cell or on the surface characterized by (1) selective binding of a specific substance and (2) a specific physiologic effect that accompanies the binding, e.g., membrane receptors for peptide hormones, neurotransmitters, antigens, complement fragments, and immunoglobulins and nuclear receptors for steroid hormones.

2. A sensory nerve terminal that responds to stimuli of various kinds; classified in various ways including by the type of stimulus and by the location in the body.

V2 receptor - The structure to which the antidiuretic hormone, arginine vasopressin binds.

mutations

DEFINITION:

1. Changes in form, quality, or some other characteristic.

2. In genetics, permanent transmissible changes in the genetic material, usually in a single gene.

See definitions for individual types of mutations under "mutation."

superfamily

DEFINITION:

1. A taxonomic category sometimes established, subordinate to an order and superior to a family. 2. Any of a group of proteins having similarities such as areas of structural homology and believed to descend from the same ancestral gene; e.g., integrins or immunoglobulins.

signaling

DEFINITION:

A molecule or chemical which cues a responsive behavior in its surrounding environment.

molecules

DEFINITION:

See definition under "molecule."

receptors

DEFINITION:

See definitions under "receptor."

molecular structures

DEFINITION:

The molecules and the manner of their arrangement in constituting a whole.

A cell

DEFINITION:

cell

DEFINITION:

1. Any one of the minute protoplasmic masses that make up organized tissue, consisting of a nucleus which is surrounded by cytoplasm which contains the various organelles and is enclosed in the cell or plasma membrane. A cell is the fundamental, structural, and functional unit of living organisms.

2. A small, more or less closed space.

neuroglial cells - The cells of the supportive tissue of the central nervous system (neuroglia); these non-neural cells are of three kinds: astrocytes, oligodendrocytes (collectively termed macroglia) and microglia.

reticular cells - The cells forming the reticular fibers of connective tissue; those forming the framework of lymph nodes, bone marrow, and spleen are part of the reticuloendothelial system and under appropriate stimulation may differentiate into macrophages.

stem cell - 1. Any precursor cell.

2. A blood cell progenitor, or mother cell, having the capacity for both replication and differentiation, and giving rise to various morphologically recognizable precursors of different blood cell lines, such as the proerythrocyte and myeloblast, which cannot self-replicate and must differentiate into more mature daughter cells.

chemical bond

DEFINITION:

The linkage between two atoms or radicals of a chemical compound.

extracellular

DEFINITION:

Outside a cell or cells.

agent

DEFINITION:

Any power, principle, or substance capable of producing an effect, whether physical, chemical, or biological.

hormone

DEFINITION:

A product of living cells that circulates in body fluids and produces a specific effect on the activity of cells remote from its point of origin; especially: one exerting a stimulatory effect on a cellular activity.

hypophysiotropic hormones - Hormones produced by the hypothalamus, usually releasing hormones (see below), which maintain the endocrine functions of cells of the adenohypophysis.

neurohormone - A hormone secreted by a specialized neuron into the bloodstream, the cerebrospinal fluid, or the intercellular spaces of the nervous system.

releasing hormones - Hormones elaborated in one structure that cause the release of hormones from another structure, such as those from the hypothalamus that act on the adenohypophysis. The term is applied to substances of established chemical identity, whereas substances of unknown chemical structure are called releasing factors .

neurotransmitter

DEFINITION:

Any of a group of substances that transmit nerve impulses across a synapse.

antigen

DEFINITION:

A usually protein or carbohydrate substance (as a toxin or enzyme) capable of stimulating an immune response.

bond

DEFINITION:

1. The linkage between two atoms or radicals of a chemical compound.

2. A mark used to indicate the number and attachment of the valences of an atom in constitutional formulas; it is represented by a pair of dots or a line between the atoms.

receptor

DEFINITION:

1. A molecular structure within a cell or on the surface characterized by (1) selective binding of a specific substance and (2) a specific physiologic effect that accompanies the binding, e.g., membrane receptors for peptide hormones, neurotransmitters, antigens, complement fragments, and immunoglobulins and nuclear receptors for steroid hormones.

2. A sensory nerve terminal that responds to stimuli of various kinds; classified in various ways including by the type of stimulus and by the location in the body.

V2 receptor - The structure to which the antidiuretic hormone, arginine vasopressin binds.

agent

DEFINITION:

Any power, principle, or substance capable of producing an effect, whether physical, chemical, or biological.

molecular sequence

DEFINITION:

See definition 3 under sequence.

affect

DEFINITION:

1. To produce an effect on; influence.

2. The external expression of emotion attached to ideas or mental representations of objects.

physiologic

DEFINITION:

Normal; not pathologic; characteristic of or conforming to the normal functioning or state of the body or a tissue or organ; physiological.

G-protein coupled receptors

DEFINITION:

G-proteins are proteins embedded in the surface membrane of cells. These proteins "receive chemical signals" from outside the cell (e.g., hormones) and "pass the signal" into the cell, so that the cell can "respond to the signal." For example, a hormone, drug, neurotransmitter, or other "signal" binds to a receptor molecule on the surface of the cell's exterior membrane. That receptor then activates the G-protein, which causes an effector inside the cell to produce a second "signal" chemical inside the cell, which causes the cell to react to the original external chemical signal.

DEFINITION:

receptors

DEFINITION:

A cell

DEFINITION:

membrane

DEFINITION:

A thin layer of tissue which covers a surface, lines a cavity, or divides a space or organ.

apical membrane - Pertaining to or located at the apex.

basolateral membrane - Pertaining to the base and sides.

plasma membrane - The structure enveloping a cell, enclosing the cytoplasm, and forming a selective permeability barrier; it consists of lipids, proteins, and some carbohydrates, the lipids thought to form a bilayer in which integral proteins are embedded to varying degrees.

postsynaptic membrane - The area of plasma membrane of a postsynaptic cell, either a muscle fiber or a neuron, that is within the synapse and has areas especially adapted for receiving neurotransmitters.

presynaptic membrane - Area of the plasma membrane of a presynaptic axon that is within the synapse and has sites (active zones) especially adapted for the release of neurotransmitters.

semipermeable membrane - A membrane that permits the passage of a solvent, such as water, but prevents the passage of the dissolved substance, or solute.

G protein

DEFINITION:

Any of a family of similar heterotrimeric proteins of the intracellular portion of the plasma membrane that bind activated receptor complexes and, through conformational changes and cyclic binding and hydrolysis of GTP, directly or indirectly effect alterations in channel gating and so couple cell surface receptors to intracellular responses. Some G proteins are named for their activities, e.g., Gs stimulates and GI inhibits enzyme activity.

membrane

DEFINITION:

A thin layer of tissue which covers a surface, lines a cavity, or divides a space or organ.

apical membrane - Pertaining to or located at the apex.

basolateral membrane - Pertaining to the base and sides.

plasma membrane - The structure enveloping a cell, enclosing the cytoplasm, and forming a selective permeability barrier; it consists of lipids, proteins, and some carbohydrates, the lipids thought to form a bilayer in which integral proteins are embedded to varying degrees.

postsynaptic membrane - The area of plasma membrane of a postsynaptic cell, either a muscle fiber or a neuron, that is within the synapse and has areas especially adapted for receiving neurotransmitters.

presynaptic membrane - Area of the plasma membrane of a presynaptic axon that is within the synapse and has sites (active zones) especially adapted for the release of neurotransmitters.

semipermeable membrane - A membrane that permits the passage of a solvent, such as water, but prevents the passage of the dissolved substance, or solute.

GPCR

DEFINITION:

G-protein-coupled receptor.

G protein

DEFINITION:

Any of a family of similar heterotrimeric proteins of the intracellular portion of the plasma membrane that bind activated receptor complexes and, through conformational changes and cyclic binding and hydrolysis of GTP, directly or indirectly effect alterations in channel gating and so couple cell surface receptors to intracellular responses. Some G proteins are named for their activities, e.g., Gs stimulates and GI inhibits enzyme activity.

bound

DEFINITION:

1. Having formed a weak, reversible chemical bond, e.g., antigen to antibody or hormone to receptor.

2. Constrained by or as if by bonds; confined, obliged.

3. Enclosed in a binding or cover.

4. Resolved, determined; also, sure.

5. Intending to go.

6. Limit, boundary.

7. Leap, jump.

8. Rebound, bounce.

9. Spring, bounce.

agent

DEFINITION:

Any power, principle, or substance capable of producing an effect, whether physical, chemical, or biological.

vasopressin-2 receptor

DEFINITION:

The molecular structure within a cell or on the surface to which the antidiuretic hormone, arginine vasopressin, binds.

V2R

DEFINITION:

Vasopressin-2 receptor.

GPCR

DEFINITION:

G-protein-coupled receptor.

basolateral membranes

DEFINITION:

The layer of plasma membrane of epithelial cells that is adjacent to the basement membrane and separated from the apical membrane by the zonula occludens.

principal cells

DEFINITION:

1. The fundamental cells of an organ, which usually have a specific function.

2. The principal cells are the chief cells, i.e., the most abundant cells of the parathyroid glands, being polygonal epithelial cells with a granular cytoplasm and vesicular nuclei, arranged in plates or cords, and which are rich in glycogen: the clear cells are more numerous and have relatively large nuclei and clear cytoplasm with few granules, while the dark cells are smaller with smaller and darker nuclei and finely granular cytoplasm with many granules. Intermediate forms also exist.

kidney collecting duct

DEFINITION:

Also known as the tubulus renalis colligens , or renal collecting tubule: that structure of the kidney consisting of the arcuate renal tubule, straight collecting tubule, and papillary duct considered together.

binds

DEFINITION:

1. To wrap with a binder or bandage.

2. To form a weak, reversible chemical bond, e.g., antigen to antibody or hormone to receptor.

extracellular

DEFINITION:

Outside a cell or cells.

agent

DEFINITION:

Any power, principle, or substance capable of producing an effect, whether physical, chemical, or biological.

arginine vasopressin

DEFINITION:

Vasopressin containing arginine, as that from most mammals, including man.

AVP

DEFINITION:

Arginine vasopressin.

hormone

DEFINITION:

A product of living cells that circulates in body fluids and produces a specific effect on the activity of cells remote from its point of origin; especially: one exerting a stimulatory effect on a cellular activity.

hypophysiotropic hormones - Hormones produced by the hypothalamus, usually releasing hormones (see below), which maintain the endocrine functions of cells of the adenohypophysis.

neurohormone - A hormone secreted by a specialized neuron into the bloodstream, the cerebrospinal fluid, or the intercellular spaces of the nervous system.

releasing hormones - Hormones elaborated in one structure that cause the release of hormones from another structure, such as those from the hypothalamus that act on the adenohypophysis. The term is applied to substances of established chemical identity, whereas substances of unknown chemical structure are called releasing factors .

kidneys

DEFINITION:

A pair of vertebrate organs situated in the body cavity near the spinal column that excrete waste products of metabolism, in man are bean-shaped organs about 4-1/2 inches long lying behind the peritoneum in a mass of fatty tissue, and consist chiefly of nephrons by which urine is secreted, collected, and discharged into a main cavity whence it is conveyed by the ureter to the bladder.

concentrate

DEFINITION:

1. To bring to a common center; to gather together at one point.

2. To increase the strength by diminishing the bulk of, as of a liquid; to condense.

3. A drug or other preparation that has been strengthened by the evaporation of its non-active parts.

urine

DEFINITION:

The fluid excreted by the kidneys, passed through the ureters, stored in the bladder, and discharged through the urethra. Urine, in health, has an amber color, a slight acid reaction, a peculiar odor, and a bitter, saline taste.

reabsorb

DEFINITION:

To absorb again; to undergo or to subject to reabsorption.

body water

DEFINITION:

The water content of the human body. See also "total body water."

V2R

DEFINITION:

Vasopressin-2 receptor.

AVP

DEFINITION:

Arginine vasopressin.

bind

DEFINITION:

To form a weak, reversible chemical bond, e.g., antigen to antibody or hormone to receptor.

Gs protein

DEFINITION:

A G protein that stimulates enzyme activity.

V2R

DEFINITION:

Vasopressin-2 receptor.

Gs protein

DEFINITION:

A G protein that stimulates enzyme activity.

AVP

DEFINITION:

Arginine vasopressin.

molecular sequence

DEFINITION:

See definition 3 under sequence.

body water

DEFINITION:

The water content of the human body. See also "total body water."

reabsorption

DEFINITION:

The act or process of absorbing again, as the selective absorption by the kidneys of substances (glucose, proteins, sodium, etc.) already secreted into the renal tubules, and their return to the circulating blood.

GPCR

DEFINITION:

G-protein-coupled receptor.

protein

DEFINITION:

Any of a group of complex organic compounds which contain carbon, hydrogen, oxygen, nitrogen, and usually sulfur, the characteristic element being nitrogen, and which are widely distributed in plants and animals. Proteins, the principal constituents of the protoplasm of all cells, are of high molecular weight and consist essentially of combinations of a-amino acids in peptide linkages. Twenty different amino acids are commonly found in proteins, and each protein has a unique, genetically defined amino acid sequence which determines its specific shape and function. They serve as enzymes, structural elements, hormones, immunoglobulins, etc., and are involved in oxygen transport, muscle contraction, electron transport, and other activities throughout the body, and in photosynthesis.

binding protein - any of a number of plasma proteins (See below) that bind to hormones of low solubility (chiefly the thyroid and steroid hormones), thus providing a transport system for them; some are specific for particular hormones, while others bind to any sparingly soluble hormones. Called also carrier protein or transport protein (See below).

carrier proteins - A binding protein (See above).

plasma proteins - The hundreds of different proteins present in blood plasma, including carrier proteins (such as albumin, transferrin, and haptoglobin), fibrinogen and other coagulation factors, complement components, immunoglobulins, enzyme inhibitors, precursors of substances such as angiotensin and bradykinin, and many other types of proteins.

transport protein - binding protein (See above).

amino acids

DEFINITION:

See definition for "amino acid."

sequence

DEFINITION:

1. A connected series of events or things. 2. In dysmorphology, a pattern of multiple anomalies derived from a single known or presumed prior anomaly or mechanical factor. 3. In molecular biology, often used to refer to DNA having a particular nucleotide composition or occurring in a particular region of the genome.

amino acids

DEFINITION:

See definition for "amino acid."

GPCR

DEFINITION:

G-protein-coupled receptor.

GPCRs

DEFINITION:

G-protein-coupled receptors.

GPCR

DEFINITION:

G-protein-coupled receptor.

cell membrane

DEFINITION:

Plasma membrane.

cell

DEFINITION:

1. Any one of the minute protoplasmic masses that make up organized tissue, consisting of a nucleus which is surrounded by cytoplasm which contains the various organelles and is enclosed in the cell or plasma membrane. A cell is the fundamental, structural, and functional unit of living organisms.

2. A small, more or less closed space.

neuroglial cells - The cells of the supportive tissue of the central nervous system (neuroglia); these non-neural cells are of three kinds: astrocytes, oligodendrocytes (collectively termed macroglia) and microglia.

reticular cells - The cells forming the reticular fibers of connective tissue; those forming the framework of lymph nodes, bone marrow, and spleen are part of the reticuloendothelial system and under appropriate stimulation may differentiate into macrophages.

stem cell - 1. Any precursor cell.

2. A blood cell progenitor, or mother cell, having the capacity for both replication and differentiation, and giving rise to various morphologically recognizable precursors of different blood cell lines, such as the proerythrocyte and myeloblast, which cannot self-replicate and must differentiate into more mature daughter cells.

transmembrane domains

DEFINITION:

The compact globular structures composed of several sections of a polypeptide chain that constitute the recognizable units of the tertiary structure of a protein. These domains extend across a membrane, usually referring to protein subunits that are exposed on both sides of a cell membrane. For an example, click here.

GPCR

DEFINITION:

G-protein-coupled receptor.

membrane

DEFINITION:

A thin layer of tissue which covers a surface, lines a cavity, or divides a space or organ.

apical membrane - Pertaining to or located at the apex.

basolateral membrane - Pertaining to the base and sides.

plasma membrane - The structure enveloping a cell, enclosing the cytoplasm, and forming a selective permeability barrier; it consists of lipids, proteins, and some carbohydrates, the lipids thought to form a bilayer in which integral proteins are embedded to varying degrees.

postsynaptic membrane - The area of plasma membrane of a postsynaptic cell, either a muscle fiber or a neuron, that is within the synapse and has areas especially adapted for receiving neurotransmitters.

presynaptic membrane - Area of the plasma membrane of a presynaptic axon that is within the synapse and has sites (active zones) especially adapted for the release of neurotransmitters.

semipermeable membrane - A membrane that permits the passage of a solvent, such as water, but prevents the passage of the dissolved substance, or solute.

extracellular

DEFINITION:

Outside a cell or cells.

extracellular loops

DEFINITION:

The turns or sharp curves in a cordlike structure appearing outside a cell's membrane, usually referring to a protein whose subunits are exposed on both sides of a cell membrane. For an example, click here.

cell

DEFINITION:

1. Any one of the minute protoplasmic masses that make up organized tissue, consisting of a nucleus which is surrounded by cytoplasm which contains the various organelles and is enclosed in the cell or plasma membrane. A cell is the fundamental, structural, and functional unit of living organisms.

2. A small, more or less closed space.

neuroglial cells - The cells of the supportive tissue of the central nervous system (neuroglia); these non-neural cells are of three kinds: astrocytes, oligodendrocytes (collectively termed macroglia) and microglia.

reticular cells - The cells forming the reticular fibers of connective tissue; those forming the framework of lymph nodes, bone marrow, and spleen are part of the reticuloendothelial system and under appropriate stimulation may differentiate into macrophages.

stem cell - 1. Any precursor cell.

2. A blood cell progenitor, or mother cell, having the capacity for both replication and differentiation, and giving rise to various morphologically recognizable precursors of different blood cell lines, such as the proerythrocyte and myeloblast, which cannot self-replicate and must differentiate into more mature daughter cells.

intracellular loops

DEFINITION:

Those portions of the beaded, cord-like structure of a V2R (See diagram here) situated within a cell's membrane.

cell

DEFINITION:

1. Any one of the minute protoplasmic masses that make up organized tissue, consisting of a nucleus which is surrounded by cytoplasm which contains the various organelles and is enclosed in the cell or plasma membrane. A cell is the fundamental, structural, and functional unit of living organisms.

2. A small, more or less closed space.

neuroglial cells - The cells of the supportive tissue of the central nervous system (neuroglia); these non-neural cells are of three kinds: astrocytes, oligodendrocytes (collectively termed macroglia) and microglia.

reticular cells - The cells forming the reticular fibers of connective tissue; those forming the framework of lymph nodes, bone marrow, and spleen are part of the reticuloendothelial system and under appropriate stimulation may differentiate into macrophages.

stem cell - 1. Any precursor cell.

2. A blood cell progenitor, or mother cell, having the capacity for both replication and differentiation, and giving rise to various morphologically recognizable precursors of different blood cell lines, such as the proerythrocyte and myeloblast, which cannot self-replicate and must differentiate into more mature daughter cells.

extracellular loops

DEFINITION:

The turns or sharp curves in a cordlike structure appearing outside a cell's membrane, usually referring to a protein whose subunits are exposed on both sides of a cell membrane. For an example, click here.

carboxy-terminus

DEFINITION:

The intracellular tail end of the vasopressin-2 receptor (V2R). See diagram.

cell

DEFINITION:

1. Any one of the minute protoplasmic masses that make up organized tissue, consisting of a nucleus which is surrounded by cytoplasm which contains the various organelles and is enclosed in the cell or plasma membrane. A cell is the fundamental, structural, and functional unit of living organisms.

2. A small, more or less closed space.

neuroglial cells - The cells of the supportive tissue of the central nervous system (neuroglia); these non-neural cells are of three kinds: astrocytes, oligodendrocytes (collectively termed macroglia) and microglia.

reticular cells - The cells forming the reticular fibers of connective tissue; those forming the framework of lymph nodes, bone marrow, and spleen are part of the reticuloendothelial system and under appropriate stimulation may differentiate into macrophages.

stem cell - 1. Any precursor cell.

2. A blood cell progenitor, or mother cell, having the capacity for both replication and differentiation, and giving rise to various morphologically recognizable precursors of different blood cell lines, such as the proerythrocyte and myeloblast, which cannot self-replicate and must differentiate into more mature daughter cells.

intracellular loops

DEFINITION:

Those portions of the beaded, cord-like structure of a V2R (See diagram here) situated within a cell's membrane.

transmembrane domains

DEFINITION:

The compact globular structures composed of several sections of a polypeptide chain that constitute the recognizable units of the tertiary structure of a protein. These domains extend across a membrane, usually referring to protein subunits that are exposed on both sides of a cell membrane. For an example, click here.

extracellular loops

DEFINITION:

The turns or sharp curves in a cordlike structure appearing outside a cell's membrane, usually referring to a protein whose subunits are exposed on both sides of a cell membrane. For an example, click here.

intracellular loops

DEFINITION:

Those portions of the beaded, cord-like structure of a V2R (See diagram here) situated within a cell's membrane.

GPCR

DEFINITION:

G-protein-coupled receptor.

GPCRs

DEFINITION:

G-protein-coupled receptors.

amino

DEFINITION:

The monovalent chemical group -NH2. As a prefix (amino-), it indicates the presence in a compound of the group -NH2.

intracellular loops

DEFINITION:

Those portions of the beaded, cord-like structure of a V2R (See diagram here) situated within a cell's membrane.

carboxy

DEFINITION:

Carboxy, as in "carboxy-terminal V2 receptor fragment" means the last third of the V2 receptor protein (V2-tail). The V2-tail is a fragment that contains only the last 130 amino acids starting at position 243 within the receptor sequence (T. Schoneberg).

V2R

DEFINITION:

Vasopressin-2 receptor.

GPCR

DEFINITION:

G-protein-coupled receptor.

GPCRs

DEFINITION:

G-protein-coupled receptors.

G

DEFINITION:

As G - Symbol for "gauss," "giga-," "gravida," and "guanine" or "guanosine."

transmembrane domains

DEFINITION:

The compact globular structures composed of several sections of a polypeptide chain that constitute the recognizable units of the tertiary structure of a protein. These domains extend across a membrane, usually referring to protein subunits that are exposed on both sides of a cell membrane. For an example, click here.

transmembrane domains

DEFINITION:

The compact globular structures composed of several sections of a polypeptide chain that constitute the recognizable units of the tertiary structure of a protein. These domains extend across a membrane, usually referring to protein subunits that are exposed on both sides of a cell membrane. For an example, click here.

membrane

DEFINITION:

A thin layer of tissue which covers a surface, lines a cavity, or divides a space or organ.

apical membrane - Pertaining to or located at the apex.

basolateral membrane - Pertaining to the base and sides.

plasma membrane - The structure enveloping a cell, enclosing the cytoplasm, and forming a selective permeability barrier; it consists of lipids, proteins, and some carbohydrates, the lipids thought to form a bilayer in which integral proteins are embedded to varying degrees.

postsynaptic membrane - The area of plasma membrane of a postsynaptic cell, either a muscle fiber or a neuron, that is within the synapse and has areas especially adapted for receiving neurotransmitters.

presynaptic membrane - Area of the plasma membrane of a presynaptic axon that is within the synapse and has sites (active zones) especially adapted for the release of neurotransmitters.

semipermeable membrane - A membrane that permits the passage of a solvent, such as water, but prevents the passage of the dissolved substance, or solute.

extracellular loops

DEFINITION:

The turns or sharp curves in a cordlike structure appearing outside a cell's membrane, usually referring to a protein whose subunits are exposed on both sides of a cell membrane. For an example, click here.

transmembrane domains

DEFINITION:

The compact globular structures composed of several sections of a polypeptide chain that constitute the recognizable units of the tertiary structure of a protein. These domains extend across a membrane, usually referring to protein subunits that are exposed on both sides of a cell membrane. For an example, click here.

transmembrane domains

DEFINITION:

The compact globular structures composed of several sections of a polypeptide chain that constitute the recognizable units of the tertiary structure of a protein. These domains extend across a membrane, usually referring to protein subunits that are exposed on both sides of a cell membrane. For an example, click here.

mutations

DEFINITION:

1. Changes in form, quality, or some other characteristic.

2. In genetics, permanent transmissible changes in the genetic material, usually in a single gene.

See definitions for individual types of mutations under "mutation."

receptor

DEFINITION:

1. A molecular structure within a cell or on the surface characterized by (1) selective binding of a specific substance and (2) a specific physiologic effect that accompanies the binding, e.g., membrane receptors for peptide hormones, neurotransmitters, antigens, complement fragments, and immunoglobulins and nuclear receptors for steroid hormones.

2. A sensory nerve terminal that responds to stimuli of various kinds; classified in various ways including by the type of stimulus and by the location in the body.

V2 receptor - The structure to which the antidiuretic hormone, arginine vasopressin binds.

GPCR

DEFINITION:

G-protein-coupled receptor.

intracellular

DEFINITION:

Situated or occurring within a cell or cells.

agent

DEFINITION:

Any power, principle, or substance capable of producing an effect, whether physical, chemical, or biological.

binds

DEFINITION:

1. To wrap with a binder or bandage.

2. To form a weak, reversible chemical bond, e.g., antigen to antibody or hormone to receptor.

transmembrane domains

DEFINITION:

The compact globular structures composed of several sections of a polypeptide chain that constitute the recognizable units of the tertiary structure of a protein. These domains extend across a membrane, usually referring to protein subunits that are exposed on both sides of a cell membrane. For an example, click here.

cell membrane

DEFINITION:

Plasma membrane.

trigger

DEFINITION:

1. To initiate, actuate, or set off.

2. To fire by pulling a trigger.

3. A movable lever that activates a device when it is squeezed; especially, the part of a firearm lock moved by the finger to fire a gun.

GPCR

DEFINITION:

G-protein-coupled receptor.

extracellular

DEFINITION:

Outside a cell or cells.

bind

DEFINITION:

To form a weak, reversible chemical bond, e.g., antigen to antibody or hormone to receptor.

extracellular loops

DEFINITION:

The turns or sharp curves in a cordlike structure appearing outside a cell's membrane, usually referring to a protein whose subunits are exposed on both sides of a cell membrane. For an example, click here.

GPCRs

DEFINITION:

G-protein-coupled receptors.

amino acid

DEFINITION:

An amphoteric organic acid containing the amino group NH2; esp.: any of the alpha-amino acids that are the chief components of proteins and are synthesized by living cells or are obtained as essential components of the diet.

GPCR

DEFINITION:

G-protein-coupled receptor.

GPCRs

DEFINITION:

G-protein-coupled receptors.

cysteine

DEFINITION:

Chemical name: 2-amino-3-mercaptopropanoic acid. A sulfur-containing nonessential amino acid produced by the enzymatic or acid hydrolysis of proteins. It is easily oxidized to cystine, is sometimes found in the urine, and has limited detoxification properties. Symbols Cys and C.

amino acid

DEFINITION:

An amphoteric organic acid containing the amino group NH2; esp.: any of the alpha-amino acids that are the chief components of proteins and are synthesized by living cells or are obtained as essential components of the diet.

extracellular loops

DEFINITION:

The turns or sharp curves in a cordlike structure appearing outside a cell's membrane, usually referring to a protein whose subunits are exposed on both sides of a cell membrane. For an example, click here.

disulfide bridge

DEFINITION:

See disulfide bond.

transmembrane

DEFINITION:

Extending across a membrane, usually referring to a protein subunit that is exposed on both sides of a cell membrane.

GPCRs

DEFINITION:

G-protein-coupled receptors.

synthesized

DEFINITION:

Produced by means of synthesis.

cell

DEFINITION:

1. Any one of the minute protoplasmic masses that make up organized tissue, consisting of a nucleus which is surrounded by cytoplasm which contains the various organelles and is enclosed in the cell or plasma membrane. A cell is the fundamental, structural, and functional unit of living organisms.

2. A small, more or less closed space.

neuroglial cells - The cells of the supportive tissue of the central nervous system (neuroglia); these non-neural cells are of three kinds: astrocytes, oligodendrocytes (collectively termed macroglia) and microglia.

reticular cells - The cells forming the reticular fibers of connective tissue; those forming the framework of lymph nodes, bone marrow, and spleen are part of the reticuloendothelial system and under appropriate stimulation may differentiate into macrophages.

stem cell - 1. Any precursor cell.

2. A blood cell progenitor, or mother cell, having the capacity for both replication and differentiation, and giving rise to various morphologically recognizable precursors of different blood cell lines, such as the proerythrocyte and myeloblast, which cannot self-replicate and must differentiate into more mature daughter cells.

cell membrane

DEFINITION:

Plasma membrane.

GPCRs

DEFINITION:

G-protein-coupled receptors.

GPCR

DEFINITION:

G-protein-coupled receptor.

third intracellular loop

DEFINITION:

See schematic drawing of the V2R.

third intracellular loop

DEFINITION:

See schematic drawing of the V2R.

carboxy-terminus

DEFINITION:

The intracellular tail end of the vasopressin-2 receptor (V2R). See diagram.

GPCR

DEFINITION:

G-protein-coupled receptor.

extracellular

DEFINITION:

Outside a cell or cells.

agent

DEFINITION:

Any power, principle, or substance capable of producing an effect, whether physical, chemical, or biological.

G

DEFINITION:

As G - Symbol for "gauss," "giga-," "gravida," and "guanine" or "guanosine."

hormone

DEFINITION:

A product of living cells that circulates in body fluids and produces a specific effect on the activity of cells remote from its point of origin; especially: one exerting a stimulatory effect on a cellular activity.

hypophysiotropic hormones - Hormones produced by the hypothalamus, usually releasing hormones (see below), which maintain the endocrine functions of cells of the adenohypophysis.

neurohormone - A hormone secreted by a specialized neuron into the bloodstream, the cerebrospinal fluid, or the intercellular spaces of the nervous system.

releasing hormones - Hormones elaborated in one structure that cause the release of hormones from another structure, such as those from the hypothalamus that act on the adenohypophysis. The term is applied to substances of established chemical identity, whereas substances of unknown chemical structure are called releasing factors .

G protein

DEFINITION:

Any of a family of similar heterotrimeric proteins of the intracellular portion of the plasma membrane that bind activated receptor complexes and, through conformational changes and cyclic binding and hydrolysis of GTP, directly or indirectly effect alterations in channel gating and so couple cell surface receptors to intracellular responses. Some G proteins are named for their activities, e.g., Gs stimulates and GI inhibits enzyme activity.

GPCR

DEFINITION:

G-protein-coupled receptor.

G protein

DEFINITION:

Any of a family of similar heterotrimeric proteins of the intracellular portion of the plasma membrane that bind activated receptor complexes and, through conformational changes and cyclic binding and hydrolysis of GTP, directly or indirectly effect alterations in channel gating and so couple cell surface receptors to intracellular responses. Some G proteins are named for their activities, e.g., Gs stimulates and GI inhibits enzyme activity.

GPCR

DEFINITION:

G-protein-coupled receptor.

agent

DEFINITION:

Any power, principle, or substance capable of producing an effect, whether physical, chemical, or biological.

G proteins

DEFINITION:

Any of a family of similar heterotrimeric proteins of the intracellular portion of the plasma membrane that bind activated receptor complexes and, through conformational changes and cyclic binding and hydrolysis of GTP, directly or indirectly effect alterations in channel gating and so couple cell surface receptors to intracellular responses. Some G proteins are named for their activities, e.g., Gs stimulates and GI inhibits enzyme activity.

alpha

DEFINITION:

1. The first letter of the Greek alphabet (A or α).

2. Something first; beginning.

beta

DEFINITION:

[B, β] The second letter of the Greek alphabet.

As Beta - The beets, a genus of herbaceous plants of the family Chenopodiaceae. Beta vulgaris (L.) is the sugar beet, a commercial source of sucrose. The leafy tops of beets are rich in oxalates and can cause oxalate poisoning in animals that eat them in large amounts.

G protein

DEFINITION:

Any of a family of similar heterotrimeric proteins of the intracellular portion of the plasma membrane that bind activated receptor complexes and, through conformational changes and cyclic binding and hydrolysis of GTP, directly or indirectly effect alterations in channel gating and so couple cell surface receptors to intracellular responses. Some G proteins are named for their activities, e.g., Gs stimulates and GI inhibits enzyme activity.

molecular sequence

DEFINITION:

See definition 3 under sequence.

subunit

DEFINITION:

Subordinate to, subordinate portion of, or subdivision of a unit.

GPCRs

DEFINITION:

G-protein-coupled receptors.

alpha

DEFINITION:

1. The first letter of the Greek alphabet (A or α).

2. Something first; beginning.

alpha

DEFINITION:

1. The first letter of the Greek alphabet (A or α).

2. Something first; beginning.

GPCR

DEFINITION:

G-protein-coupled receptor.

GPCR

DEFINITION:

G-protein-coupled receptor.

GPCR

DEFINITION:

G-protein-coupled receptor.

G protein

DEFINITION:

Any of a family of similar heterotrimeric proteins of the intracellular portion of the plasma membrane that bind activated receptor complexes and, through conformational changes and cyclic binding and hydrolysis of GTP, directly or indirectly effect alterations in channel gating and so couple cell surface receptors to intracellular responses. Some G proteins are named for their activities, e.g., Gs stimulates and GI inhibits enzyme activity.

third intracellular loop

DEFINITION:

See schematic drawing of the V2R.

GPCRs

DEFINITION:

G-protein-coupled receptors.

G protein

DEFINITION:

Any of a family of similar heterotrimeric proteins of the intracellular portion of the plasma membrane that bind activated receptor complexes and, through conformational changes and cyclic binding and hydrolysis of GTP, directly or indirectly effect alterations in channel gating and so couple cell surface receptors to intracellular responses. Some G proteins are named for their activities, e.g., Gs stimulates and GI inhibits enzyme activity.

GPCR

DEFINITION:

G-protein-coupled receptor.

third intracellular loop

DEFINITION:

See schematic drawing of the V2R.

G protein

DEFINITION:

Any of a family of similar heterotrimeric proteins of the intracellular portion of the plasma membrane that bind activated receptor complexes and, through conformational changes and cyclic binding and hydrolysis of GTP, directly or indirectly effect alterations in channel gating and so couple cell surface receptors to intracellular responses. Some G proteins are named for their activities, e.g., Gs stimulates and GI inhibits enzyme activity.

GPCR

DEFINITION:

G-protein-coupled receptor.

G proteins

DEFINITION:

Any of a family of similar heterotrimeric proteins of the intracellular portion of the plasma membrane that bind activated receptor complexes and, through conformational changes and cyclic binding and hydrolysis of GTP, directly or indirectly effect alterations in channel gating and so couple cell surface receptors to intracellular responses. Some G proteins are named for their activities, e.g., Gs stimulates and GI inhibits enzyme activity.

mutations

DEFINITION:

1. Changes in form, quality, or some other characteristic.

2. In genetics, permanent transmissible changes in the genetic material, usually in a single gene.

See definitions for individual types of mutations under "mutation."

GPCRs

DEFINITION:

G-protein-coupled receptors.

GPCR

DEFINITION:

G-protein-coupled receptor.

mutation

DEFINITION:

frameshift mutation - A mutation resulting from an addition or subtraction that is not an exact multiple of 3 base pairs in a coding sequence. From the point of mutation onwards, base triplets (codons) are read out of phase; the reading frame of the gene is changed, and a completely different set of amino acids is made into protein.

loss-of-function mutation - Impairment of the function of a gene caused by mutation.

missense mutation - A mutation that changes a codon so that it codes for a different amino acid.

nonsense mutation - A mutation in which one of the three terminator codons in the mRNA (UAG, amber; UAA, ochre; UGA, umber or opal), used to signal the end of a polypeptide, appears in the middle of a genetic message, causes premature termination of transcription, and releases incomplete, generally nonfunctional polypeptides from the ribosome.

functional

DEFINITION:

GPCR

DEFINITION:

GPCR

DEFINITION:

vasopressin-2 receptor

DEFINITION:

The molecular structure within a cell or on the surface to which the antidiuretic hormone, arginine vasopressin, binds.

V2R

DEFINITION:

Vasopressin-2 receptor.

gene

DEFINITION:

A segment of a DNA molecule that contains all the information required for synthesis of a product (polypeptide chain or RNA molecule), including both coding and non-coding sequences. It is the biological unit of heredity, self-reproducing, and transmitted from parent to progeny. Each gene has a specific position (locus) on the chromosome map. From the standpoint of function, genes are conceived of as structural, operator, and regulatory genes.

wild-type gene - The normal allele of a gene, sometimes symbolized by +.

X-linked gene - A gene carried on the X chromosome; the corresponding trait, whether dominant or recessive, is always expressed in males, who have only one X chromosome. X linkage is used sometimes synonymously with sex linkage since no genetic disorders have as yet been associated with genes on the Y chromosome.

mutated

DEFINITION:

1. Changed in form, quality, or some other characteristic. 2. In genetics, having undergone a permanent transmissible change in the genetic material, usually in a single gene. Also, an individual exhibiting such a change.

X-linked

DEFINITION:

See under gene.

NDI

DEFINITION:

Nephrogenic diabetes insipidus.

mutations

DEFINITION:

1. Changes in form, quality, or some other characteristic.

2. In genetics, permanent transmissible changes in the genetic material, usually in a single gene.

See definitions for individual types of mutations under "mutation."

V2R

DEFINITION:

Vasopressin-2 receptor.

mutations

DEFINITION:

1. Changes in form, quality, or some other characteristic.

2. In genetics, permanent transmissible changes in the genetic material, usually in a single gene.

See definitions for individual types of mutations under "mutation."

V2Rs

DEFINITION:

Vasopressin-2 receptors.

render

DEFINITION:

1. To extract (as lard) by heating.

2. To give to another; yield.

3. To give in return.

4. To do (a service) for another.

5. To cause to be or become; make.

6. To reproduce or represent by artistic or verbal means.

amino acid

DEFINITION:

An amphoteric organic acid containing the amino group NH2; esp.: any of the alpha-amino acids that are the chief components of proteins and are synthesized by living cells or are obtained as essential components of the diet.

mutation

DEFINITION:

frameshift mutation - A mutation resulting from an addition or subtraction that is not an exact multiple of 3 base pairs in a coding sequence. From the point of mutation onwards, base triplets (codons) are read out of phase; the reading frame of the gene is changed, and a completely different set of amino acids is made into protein.

loss-of-function mutation - Impairment of the function of a gene caused by mutation.

missense mutation - A mutation that changes a codon so that it codes for a different amino acid.

nonsense mutation - A mutation in which one of the three terminator codons in the mRNA (UAG, amber; UAA, ochre; UGA, umber or opal), used to signal the end of a polypeptide, appears in the middle of a genetic message, causes premature termination of transcription, and releases incomplete, generally nonfunctional polypeptides from the ribosome.

mutation

DEFINITION:

frameshift mutation - A mutation resulting from an addition or subtraction that is not an exact multiple of 3 base pairs in a coding sequence. From the point of mutation onwards, base triplets (codons) are read out of phase; the reading frame of the gene is changed, and a completely different set of amino acids is made into protein.

loss-of-function mutation - Impairment of the function of a gene caused by mutation.

missense mutation - A mutation that changes a codon so that it codes for a different amino acid.

nonsense mutation - A mutation in which one of the three terminator codons in the mRNA (UAG, amber; UAA, ochre; UGA, umber or opal), used to signal the end of a polypeptide, appears in the middle of a genetic message, causes premature termination of transcription, and releases incomplete, generally nonfunctional polypeptides from the ribosome.

mutation

DEFINITION:

frameshift mutation - A mutation resulting from an addition or subtraction that is not an exact multiple of 3 base pairs in a coding sequence. From the point of mutation onwards, base triplets (codons) are read out of phase; the reading frame of the gene is changed, and a completely different set of amino acids is made into protein.

loss-of-function mutation - Impairment of the function of a gene caused by mutation.

missense mutation - A mutation that changes a codon so that it codes for a different amino acid.

nonsense mutation - A mutation in which one of the three terminator codons in the mRNA (UAG, amber; UAA, ochre; UGA, umber or opal), used to signal the end of a polypeptide, appears in the middle of a genetic message, causes premature termination of transcription, and releases incomplete, generally nonfunctional polypeptides from the ribosome.

V2R

DEFINITION:

Vasopressin-2 receptor.

G protein

DEFINITION:

Any of a family of similar heterotrimeric proteins of the intracellular portion of the plasma membrane that bind activated receptor complexes and, through conformational changes and cyclic binding and hydrolysis of GTP, directly or indirectly effect alterations in channel gating and so couple cell surface receptors to intracellular responses. Some G proteins are named for their activities, e.g., Gs stimulates and GI inhibits enzyme activity.